Mining bee, possibly a tawny mining bee (Andrena fulva), going for flower to flower in a patch of lesser celandine, adding a little to its already bulging pollen baskets at each one.
Catkins aren’t there to attract insects, but to have the pollen get to the female flowers by being carried on the breeze. But this tortoiseshell butterfly was gorging itself on the pollen of a pussy willow by the canal at Compton.